I did a write up on Tiffany stone since some people insist that it has only been found in once place in the world, which is not true.
There are a lot of misconceptions about Tiffany stone such as what it actually is. Some people refer to it as ice cream opal even though Tiffany stone is not opal. Some people refer to it as bertrandite even though Tiffany stone is not the mineral bertrandite, which is found in many locations around the world. Tiffany stone is not a particular mineral but rather a mix of up to 16 different minerals including fluorite, quartz, calcite, dolomite, opal, chalcedony, bertrandite, etc. Each of these minerals may or not be present in a particular piece. For example bertrandite is such a rare mineral in the ore, I think it was something like .04%, that most Tiffany stone does not contain any bertrandite.
Another common misconception is that Tiffany stone only comes from one location, which is the Brush –Wellman Mine in Utah. This is a very persistent myth that I think is to keep the price artificially inflated especially since collecting at the mine is no longer allowed. About 10 years ago I saw this material retailing for $500 a pound!!! The price has dropped drastically since then I think in large part because the material from Utah has a bad reputation of often being highly friable (easy disintegrates when working with it). So basically people were spending $500 a pound on a major gamble. Last I checked the average price was now running $25 a pound. Tiffany stone has actually been found in three locations in Utah and there are two locations I am aware of in Nevada.
There is a similar claim about red beryl, which some also claim also only occurs in one place in Utah. Fact is that red beryl is found in two locations in Utah and also has been found in New Mexico. So again stories of being more rare are often done to artificially inflate prices.
Most of the Nevada Tiffany stone is pretty stable and the only major difference I have found in composition between the Utah and Nevada material is the fact that the Nevada material often has honey calcite and occasionally green calcite present as well as the white calcite. The Utah Tiffany stone only has white calcite.